Beetroot Juice: New Sports Drink?

Beetroot Juice: New Sports Drink?

Posted on 09/21/2011 at 10:00:14 AM by Student Blogger

By Jon C.

It is widely accepted that increased intake of the preservative
sodium nitrite found in processed meats such as deli meats, bacon,
and hot dogs is associated with negative health outcomes for
certain subgroups of the population (1). These associations
have resulted in dietary nitrates and nitrites receiving a “bad
name.” However, scientists have been quick to point out that
diets proven to be beneficial for cardiovascular health contain
high amounts of fruits and vegetables, are low in sodium and
contain polyphenols, potassium, fiber, and, you guessed it,
nitrate! (2) If dietary nitrates and its reduced form,
nitrite, are so harmful, then why do we encourage consumption of
fruits and vegetables containing these compounds?

Interestingly, dietary nitrate can reduce blood pressure through
conversion to nitric oxide resulting in increased vasodilatation
(3). Thus, it stands to reason that enhanced nitrate intake
contributes to the cardioprotective effect of dark green leafy
vegetables, which are a particularly rich source of nitrate
(2). Evidence is emerging that consumption of dietary nitrate
not only has positive effects on blood pressure, but that it also
has the ability to enhance some parameters of exercise
performance!(3)

In a recent study, subjects consuming 0.5L of beetroot juice prior
to exercise exhibited a reduction in systolic blood pressure, as
well as decreased oxygen consumption during walking and running
(4). Indeed, beetroot juice is a rich source of dietary nitrate as
well as other metabolically active compounds including antioxidants
and polyphenols. In order to control for these variables, the
authors of this study removed nitrate from the beetroot juice to
use as a control. It became apparent that the positive effects on
exercise observed in this study were due to the nitrate content of
beetroot juice. Importantly, results from this study as well as
others indicate dietary nitrate increased time to exhaustion in
constant speed severe intensity running and cycling as well as
decreasing the oxygen cost of exercise, indicating improved
exercise economy (3, 5). While the mechanisms by which
dietary nitrate improves these parameters remains to be fully
understood, by use of a nitrate free beetroot juice, the authors
definitively show that dietary nitrate has a positive physiological
response to exercise.

These studies provide a valuable dietary modification of exercise
performance. By reducing the oxygen cost at moderate and severe
intensity running, one is reducing the energy cost of
running. According to the authors, 4 days of dietary nitrate
supplementation induced improvements equivalent to those observed
following 6-9 weeks of physical training (4). Ideally
enhanced running economy translates to enhanced endurance; however
this parameter was not assessed during this study. Maybe before my
next run, I will give beetroot juice a try!